[llvm] [MachineBasicBlock] Fix use after free in SplitCriticalEdge (PR #68786)

[Jay Foad via llvm-commits]

================
@@ -14,6 +14,7 @@
 #define LLVM_CODEGEN_MACHINEBASICBLOCK_H
 
 #include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SmallPtrSet.h"
----------------
jayfoad wrote:

Don't need this

https://github.com/llvm/llvm-project/pull/68786